Modern data communication networks offer a wide range of services. Recently, an increasing variety of those services have involved real-time communication of data, typically for real-time processing and presentation of information to a user of a client device. Examples of these kinds of ‘streaming’ communication services include real-time transmission of audio and video information in one or more directions, e.g. for sending radio programs, television programs, movies or the like to the user's client device for presentation, or for telephone or videophone type calls via the data network.
Modern data communication networks transport the data to and from client devices in packets. Packet data transport typically utilizes layered protocols in the Internet Protocol (IP) suite. Data in a large number of individual packet transported through a packet network, however, often is subject to packet delay and/or delay variation (jitter).
With the explosion in the number and types of user devices and the explosion in the variety of service, more and more networks support communication of streaming (and other type of) services over wireless links. Streaming type applications may be adversely impacted by delay or jitter in the delivery of packets to the client device.
Conventional wireless communication protocols such as 802.11 for packet data transport utilize access points (AP) as the wireless access node that communicates over the air with the wireless or mobile device of the user. 802.11 communications typically provide local wireless links (as opposite to longer/wider area links offered by public/cellular/wide are types of networks). The access point in an 802.11 network determines an appropriate channel among a plurality of possible 802.11 channels for communicating with one or more client devices within range of the access point. This channel determination is made through a process known as sounding (i.e. scanning of channels). To perform sounding, the AP stops transmitting data to the client device, and begins scanning the possible 802.11 channels.
However, this scanning process typically takes 20 ms-50 ms per channel. For an arrangement, with a substantial number of possible channels, the scanning operation at times may take a 30 to 60 seconds, e.g. if the access point has to scan almost all the channels to find a suitable new channel for the switching operation. Data packets intended for the client device may be buffered on the network side during the scan, to mitigate any potential for packet loss. A long total scan time results in a long interruption in streaming data transmission from the access point to the client device. The delay between packets caused by the interruption may impact output to the device user if the client device does not have a sufficient amount of buffered previously received data to continue its decoding and presentation operations for the entire time of the transmission interruption. This interruption in streaming data output may be noticeable to a user of the client device executing streaming applications (e.g. if the streaming movie freezes during playback).